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Flight Software & Embedded Systems Framework

F´ v3.0.0 Migration Guide

This guide is for users hoping to migrate from older F´ versions to F´ v3.0.0. It will discuss the major differences between older F´ versions and F´ v3.0.0+ and point out places where users will need to make.

Modeling Changes

F´v3.0.0 has switched from a baseline using the F´ XML format for modeling F´ constructs to using FPP as a modeling language. Users may continue to use XML to model components but the F´ team recommends converting to the FPP language as the XML format will not receive feature enhancements.

There is one caveat that users should be aware of: topology models. If a project wishes to use FPP as a modeling language for a given topology, they must ensure that all components used by that topology are also modeled with FPP. XML topologies can include both components modeled in XML and FPP so that projects can begin to migrate to FPP models without needing to convert everything.

fpp-from-xml is a tool included with the FPP tool suit to help convert from XML to FPP. Further information on the FPP tool suite and FPP in general can be found at:

Topology Changes

Deployments in older versions of F´ did not treat the Topology as a separate module from the deployment’s executable and entry point code. This setup is limiting and clear separation of the Topology module and the executable is now required.

In addition, deployments have been split from general executables and should use register_fprime_deployment().

This can be done with the following changes to the CMake setup:

  1. In <Deployment>/Top/CMakeLists.txt remove the entrypoint code (e.g. Main.cpp) and call register_fprime_module() instead of register_fprime_executable().

These modifications can be seen in the Ref app: Ref/Top/CMakeLists.txt

Note: the reference example also show changes necessary to run an FPP topology as discussed above.

  1. In <Deployment>/CMakeLists.txt include entrypoint code in SOURCE_FILES list, set MOD_DEPS to include your topology module and call register_fprime_deployment to setup the executable.

These modifications to Ref can be seen here: Ref/CMakeLists.txt

Inline Enumerations and Standard Enumerations

Inline enumerations within a Component are no longer supported. F´ supports enumeration models so projects should migrate to defining an enumeration model and using that type as arguments to commands, events, etc. As part of this work standard enumerations that were previously implemented as inline enumerations have now been converted. This means projects must update usage of these enumerations. In some cases these enumeration names have been slightly changes.

The best example of this is the command response enumeration. This change can be seen in the SignalGen component as shown below.

Out-of-Date Version 2 Code

this->cmdResponse_out(opCode, cmdSeq, Fw::COMMAND_OK);


Corrected Version 3 Code

this->cmdResponse_out(opCode, cmdSeq, Fw::CmdResponse::OK);


The following user-facing enumeration types must be updated.

Old Symbol Updated Symbol
Fw::COMMAND_OK Fw::CmdResponse::OK
Fw::COMMAND_BUSY Fw::CmdResponse::BUSY

Other enumerations have changed but these are typically wrapped in the autocoded layer. A complete list is found here.

CMake Options

F´ v3.0.0 has reworked the command line options to fprime-util generate to ensure that F´ is inline with CMake standard usages for CMake variables. In general, F´ no longer depends on certain settings to standard CMake variables. There are a few exceptions described below.

  1. CMAKE_BUILD_TYPE is no longer used to specify unit test builds and the user may now override it. CMAKE_BUILD_TYPE may no longer be used to detect if the current build is generating unit tests.
  2. BUILD_TESTING is now set to ON or OFF to turn on or off unit test builds. Projects needing to detect unit test builds should use if (BUILD_TESTING). This is controlled with the --ut switch through fprime-util.
  3. CMAKE_INSTALL_PREFIX is now used to set the output location of the build process (e.g. build-artifacts). This was done to fall in line with the standard CMake installation patterns.

Most users need to set these variables directly when standard build setups are desired as fprime-util will set these variables where needed. However, users needing custom setups may now set CMAKE_INSTALL_PREFIX and CMAKE_BUILD_TYPE.

Os::Task API Changes

FPP topologies will automatically generate the boilerplate code for starting active components. However, users who start their own Os::Task objects and users who run XML topologies and thus start their own tasks should be aware of changes to the Os::Task::start and ActiveComponent::start API.

Arguments to these functions are now unsigned integers in the order: priority, stack size, cpu affinity, and identifier. Each parameter comes with a default, so none need be specified. When specified on Posix systems, the OS will attempt to see these values as requested. However, when permissions are not available to set these the system will fallback to the default pthreads settings.

Calling the older Os::Task::start API will result in a compile time error.

An example of reworking a task start call is seen at:

More information is available at: